/*
 * ProGuard -- shrinking, optimization, obfuscation, and preverification of Java bytecode.
 *
 * Copyright (c) 2002-2018 GuardSquare NV
 *
 * This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public
 * License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later
 * version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along with this program; if not, write to the Free
 * Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
package proguard.shrink;

import proguard.classfile.*;
import proguard.classfile.attribute.*;
import proguard.classfile.attribute.visitor.AttributeVisitor;
import proguard.classfile.util.*;
import proguard.classfile.visitor.*;

import java.io.PrintStream;

/**
 * This ClassVisitor prints out the classes and class members that have been marked as being used (or not used).
 *
 * @see UsageMarker
 *
 * @author Eric Lafortune
 */
public class UsagePrinter extends SimplifiedVisitor implements ClassVisitor, MemberVisitor, AttributeVisitor {
    private final UsageMarker usageMarker;
    private final boolean printUnusedItems;
    private final PrintStream ps;

    // A field to remember the class name, if a header is needed for class members.
    private String className;

    /**
     * Creates a new UsagePrinter that prints to <code>System.out</code>.
     * 
     * @param usageMarker the usage marker that was used to mark the classes and class members.
     * @param printUnusedItems a flag that indicates whether only unused items should be printed, or alternatively, only
     *        used items.
     */
    public UsagePrinter(UsageMarker usageMarker, boolean printUnusedItems) {
        this(usageMarker, printUnusedItems, System.out);
    }

    /**
     * Creates a new UsagePrinter that prints to the given stream.
     * 
     * @param usageMarker the usage marker that was used to mark the classes and class members.
     * @param printUnusedItems a flag that indicates whether only unused items should be printed, or alternatively, only
     *        used items.
     * @param printStream the stream to which to print.
     */
    public UsagePrinter(UsageMarker usageMarker, boolean printUnusedItems, PrintStream printStream) {
        this.usageMarker = usageMarker;
        this.printUnusedItems = printUnusedItems;
        this.ps = printStream;
    }

    // Implementations for ClassVisitor.

    public void visitProgramClass(ProgramClass programClass) {
        if (usageMarker.isUsed(programClass)) {
            if (printUnusedItems) {
                className = programClass.getName();

                programClass.fieldsAccept(this);
                programClass.methodsAccept(this);

                className = null;
            } else {
                ps.println(ClassUtil.externalClassName(programClass.getName()));
            }
        } else {
            if (printUnusedItems) {
                ps.println(ClassUtil.externalClassName(programClass.getName()));
            }
        }
    }

    // Implementations for MemberVisitor.

    public void visitProgramField(ProgramClass programClass, ProgramField programField) {
        if (usageMarker.isUsed(programField) ^ printUnusedItems) {
            printClassNameHeader();

            ps.println("    " + ClassUtil.externalFullFieldDescription(programField.getAccessFlags(),
                programField.getName(programClass), programField.getDescriptor(programClass)));
        }
    }

    public void visitProgramMethod(ProgramClass programClass, ProgramMethod programMethod) {
        if (usageMarker.isUsed(programMethod) ^ printUnusedItems) {
            printClassNameHeader();

            ps.print("    ");
            programMethod.attributesAccept(programClass, this);
            ps.println(ClassUtil.externalFullMethodDescription(programClass.getName(), programMethod.getAccessFlags(),
                programMethod.getName(programClass), programMethod.getDescriptor(programClass)));
        }
    }

    // Implementations for AttributeVisitor.

    public void visitAnyAttribute(Clazz clazz, Attribute attribute) {}

    public void visitCodeAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute) {
        codeAttribute.attributesAccept(clazz, method, this);
    }

    public void visitLineNumberTableAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute,
        LineNumberTableAttribute lineNumberTableAttribute) {
        ps.print(lineNumberTableAttribute.getLowestLineNumber() + ":" + lineNumberTableAttribute.getHighestLineNumber()
            + ":");
    }

    // Small utility methods.

    /**
     * Prints the class name field. The field is then cleared, so it is not printed again.
     */
    private void printClassNameHeader() {
        if (className != null) {
            ps.println(ClassUtil.externalClassName(className) + ":");
            className = null;
        }
    }
}
